1. Field of the Invention
This invention generally relates to a recording/reproducing system and, more particularly, to a recording/reproducing system which can provide a predetermined restriction on recording/reproduction.
2. Description of the Related Art
In current systems of recording/reproducing an information source such as an audio or image signal, a variety of recording/reproducing systems such as a magnetic system, an optical system, and the like are proposed for, e.g., a variety of dynamic (storage) recording media including a tape-like recording medium, a disk-like recording medium, a card-like recording medium, and the like. These recording systems are put into various practical applications. These recording/reproducing systems preferably have recording/reproducing characteristics of high fidelity, as well as good operability. In addition, these systems preferably comprise functions requested by users as much as possible unless a social problem against, e.g., public order and morals, arises.
In the recording/reproducing systems as described above, recording media and recording/reproducing systems are dealt with independently. As along as recording/reproducing systems of an identical type are used, recording media have compatibility to be subjected to recording or reproduction in any apparatus. However, in some recording/reproducing systems to which no restriction for recording for the purpose of making a copy is provided, sometimes a user cannot easily record information since the recording media have compatibility.
Assuming that a recording medium which has recorded an information source is commercially available, if a purchaser makes a copy of the information source, the recording medium (copy) on which the information source is recorded by copying and one (original) on which the information source was originally recorded have an identical value. For this reason, if such copying is illegally performed in a large quantity for benefits by utilizing the compatibility of recording/reproducing systems, the value of the original recording medium on which the information source is recorded is largely reduced. In addition, the higher the fidelity of copies becomes, the lower the originality of the original recording medium becomes.
To prevent this, a countermeasure for inhibiting such copying is inevitably taken. However, a conventional copy inhibition method described below is not satisfactory for a user. More specifically, in the conventional copy inhibition method, a signal representing a predetermined inhibition code is inserted in an information source and is recorded on a recording medium. If a recording/reproducing system detects the inhibition code in a transmission signal of a recording information source, it interrupts the recording function. For example, as an information source (in this case, a digital signal) is reproduced, if a transmission format is a group of blocks (consisting of 1 to m bits), a predetermined position (nth-bit position) of each block, or a specific block, is assigned to a flag representing inhibition "0" or permission "1" of a recording operation. The flag (or a code combining the flags) is detected by a recording/reproducing system which received a reproduction signal. If the flag represents inhibition of the recording operation, the recording function is interrupted. Interruption of the recording function can be achieved by various methods, such as disconnection of a signal path. If such a countermeasure is taken for all the recording/reproducing systems of an identical type, an information source including an inhibition code can be inhibited from being copied.
However, in the conventional method, copying the information source with the inhibition code is perfectly inhibited as is recording an information source which does not reduce a value of a recording medium. Thus recording for personal use cannot be performed, either.
Upon developments of digital audio tape recorders (DATs), a conflict of interests, as described above, arises between copyrights of soft tapes for the DATs and/or conventional compact disks (CDs) and cancellation of copy inhibition for personal use that is permitted legally or by judgement.
In the recording/reproducing systems which employ a conventional copy inhibition method where restriction on copying is too complete or is not made at all, a recording/reproducing operation for personal use desired by a user cannot often be satisfied. As a result, applications of the recording/reproducing system having good performance, such as DATs, are limited, thus preventing their wide spread use.
This conflict interferes with industrial promotion of such products, and is disadvantageous for a user. Therefore, a strong demand has arisen for development of a recording/reproducing system having a predetermined copy restriction function which can provide a solution agreeable to both the copyright holder (including software industries) and the user.
In addition to a problem concerning a commercial information source, a user may want a recording/reproducing function for preventing a third party to easily copy or reproduce a source recorded by a user, except for his personal use. The conventional recording/reproducing system which does not restrict copying at all, or which employs the above-mentioned copy inhibition method cannot meet such a requirement of the user.